Telecommunications networks provide a mechanism for communicating between subscriber equipment at diverse locations. A typical telecommunications network includes a variety of electronic modules, circuits and components. Further, these modules are typically coupled together over various communications links or lines through switches, routers, and other conventional equipment.
Some networks transmit digital data. With systems transmitting digital data, one aspect that affects the quality of the services provided is the bit error rate. This is a measurement of the number of errors per second and is typically represented as a percentage of bad bits to good. For example, a bit error rate of 1 bit in 1 billion would be represented as a bit error rate of 10−9. A common specification for equipment manufacturers to meet is a maximum allowable bit error rate.
Before deploying equipment, manufacturers typically test their equipment in the lab to determine whether the equipment meets its design specifications. If not, modifications can be made until the criteria is met. These tests are accomplished with conventional test equipment which generates test signals, transmits the signals over the system in the lab, and then compares the output of the system with an expected signal. One aspect of this testing is that no errors are introduced by the connection between the test equipment and the system under test. This can be readily accomplished in a laboratory environment. However, once the equipment is deployed, the communication link between the system under test and the equipment under test may introduce errors into the process of measuring the error rate. For example, in the testing of a system with a host module and a remote module coupled over a fiber optic link, the test equipment cannot be connected over a perfect connection. Therefore, once deployed, the bit error rate for a system under test cannot readily be monitored to determine whether the performance level has changed since any connection back to the test equipment could also introduce errors.
Therefore, there is a need in the art for improvements in measuring and monitoring the bit error rate of a communication link.